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I don't understand the conflation. 'tptacek is arguing that you preferentially use secret-key crypto to public-key crypto, because public-key crypto is signific
by lvh 9y ago
I don't understand the conflation. 'tptacek is arguing that you preferentially use secret-key crypto to public-key crypto, because public-key crypto is significantly more precarious. It seems like you are raising a new point, not arguing with his.
- giaour 9y agotptacek was saying everyone should be cautious about PKI-based JWTs and provided encrypted cookies as an example of something that is rarely (if ever) implemented safely and securely with PKI cryptography. My point is that while the 'seal' function of PAST may be of questionable value, the 'sign' function is not. I think it's important to disambiguate those two uses of asymmetric cryptography.
- lvh 9y agoGotcha, thanks! That makes more sense now. I agree that they're worth examining separately, but the more general point still stands that there is a lot more that can go wrong with sign than with aead. The arguments for broken RSA-encrypted cookies apply similarly to broken signed cookies. It's not clear to me for example that an invalid curve attack against seal is intrinsically worse than a nonce (ab|re)use bug against ECDSA.